Project Abstract Due to its geographic proximity to New York City the Nassau/Suffolk metropolitan statistical area (MSA) shares many of the HIV and drug related epidemiologic concerns of Urban MSAs. HIV trends are particularly of concern for young MSM, sexually active females, and Black males who use injection drugs; individuals who fall into these categories experience rates of HIV that are alarmingly elevated relative to other members of their risk group. Understanding the factors that continue to impede risk reduction among these groups is essential to primary and secondary prevention of HIV. As a complement to traditional HIV surveillance which focuses on data from lab reports and medical providers, behavioral data collected from individuals involved in high risk activity such as men who have sex with men (MSM), injection drug users (IDU), and heterosexuals at risk for infection can augment the broad based information gleaned from traditional sources. Behavioral surveillance can identify certain emerging epidemiological trends, direct intervention efforts on populations most currently at risk, and evaluate whether current intervention goals are being met. As a Behavioral Surveillance grantee, we will conduct annual rotating surveys of the designated high risk groups MSM, IDU, and heterosexuals at risk for infection. For each MSM and IDU cycle a minimum of 500 eligible participants will be enrolled; a minimum of 450 heterosexuals at risk for HIV infection will be enrolled during the heterosexual cycle. To assess the incidence and prevalence of HIV, all cycles of the National HIV Behavioral Surveillance (NHBS) project will include a voluntary HIV testing component. The attached research plan outlines how the activities of each NHBS cycle will be completed.